Greatest Heavyweights is the USA release of a Sega Genesis boxing game. This version would have likely retained the core boxing gameplay of its Japanese counterpart but could include adjustments to rosters, names, or gameplay mechanics to better fit the US market.  The actual developers are not explicitly known but would have likely been an internal team or a licensed third-party.

Greatest Heavyweights (USA)

Great Circus Mystery Starring Mickey & Minnie, The (USA)